This invention relates to backrests for chairs. More particularly, the invention relates to a backrest that provides adjustable support to the lumbar region of the back of a user seated on a chair.
Backrests that provide lumbar support are known. Many of these have a non-adjustable lumbar support. The lumbar support is built into the back rest and may therefore be configured to provide adequate support for a typical person. In practice, such backrests provide inadequate support for people who are larger or smaller than average. Adjustable lumbar supports are also known, however, these devices tend to have complex adjustment mechanisms that are both heavy and costly.
For example, Kemmann describes an adjustable backrest in U.S. Pat. No. 4,810,033. This backrest has an outer frame that holds a deformable plate that provides lumbar support. The top portion of the plate (i.e. the region of the plate nearer the upper back of a user) is formed into a series of longitudinal slats, running from the top of the lumbar support to its center. The lower portion of the lumbar support plate (i.e. the portion which actually supports the user""s back) does not have any openings and is less flexible. A control knob is drivingly connected to the plate through a complex mechanism and is rotatably mounted to change the position of the lower portion of the plate to force the plate outwardly such that the plate provides lumbar support.
One disadvantage of lumbar adjustment mechanisms is that they utilize complex and costly adjustment mechanisms. Therefore, they tend to be provided on more expensive chairs. Thus they may be provided on chairs for executives and professionals but not on secretarial chairs who would also benefit from a more ergonomic chair. Further, due to the complexity of the mechanism, the mechanism is prone to breaking.
In accordance with one aspect of the instant invention, there is provided a backrest for supporting a person""s back having a front surface and a rear surface, the backrest comprising: a member having an outer perimeter and a flexible support section, the flexible support section having a fixed end which is connected to a portion of the perimeter and a free end positioned distal to the fixed end, the flexible support section is configured to be displaced forwardly when the free end is moved towards the fixed end; an adjustment member drivingly connected to the free end; and a locking member for retaining the free end at a fixed position with respect to the fixed end.
In one embodiment of the invention, the flexible support section biases the free end to engage the locking member.
In another embodiment, the locking member comprises a detent member for selectively receiving the adjustment member in one of a plurality of positions, the flexible support section biasing the adjustment member into retaining engagement with the detent member due to the compression of the flexible support member by the displacement of the free end towards the fixed end.
In another embodiment, the fixed end comprises an upper end and the free end comprises a lower end and the detent member comprise a plurality of vertically spaced apart members each of which has a downwardly extending recess and the adjustment member is sized to be received in each recess.
In another embodiment, the detent member comprises a plurality of vertically spaced apart members each of which has a recess to receive therein the adjustment member and support member biases the adjustment member into engagement with the recesses.
In another embodiment, the backrest has a rear face with a vertically extending opening adjacent the free end, the adjustment member is mounted at the free end of the support structure and has a handle which extends through the vertically extending opening whereby the flexible support section may be adjusted from the rear of the backrest.
In another embodiment, locking member comprises a detent and gear arrangement.
In another embodiment, the gear arrangement is mounted on a shaft and the adjustment member comprises a cam eccentrically mounted on the shaft.
In another embodiment, the adjustment member comprises an eccentrically mounted cam.
In another embodiment, the backrest comprises a frame and the member comprises a shell mounted on the frame.
In another embodiment, the frame has an opening sized to receive therein the flexible support section.
In another embodiment, the flexible support section comprises a plurality of slats extending vertically between the fixed end and the free end of the flexible support section.
In another embodiment, the slats extend from a position adjacent the fixed end to a position adjacent the free end.
In another embodiment, the perimeter section surrounds a central section in which the flexible support section is provided and, when mounted on a chair, the support structure has a vertical extent sufficient to support at least the lumbar region of the person when seated in the chair.
In another embodiment, the shell has first engagement members and the frame has second engagement members configured to engage the first engagement members whereby the engagement of the first and second engagement members retains the shell on the frame.
In another embodiment, the first engagement members and the second engagement members comprise a plurality of openings and the other of the first and second engagement members comprises projecting members that are locking received in the openings.
In another aspect of the invention, there is provided a backrest for supporting a user""s back having a front surface and a rear surface, the backrest comprising: a frame; a shell mounted on the frame, the shell having a flexible support section; and first engagement members provided an the shell and second engagement members provided on the frame, the second engagement members are configured to engage the first engagement members whereby the engagement of the first and second engagement members retains the shell on the frame.
In another embodiment, one of the first engagement members and the second engagement members comprise a plurality of openings and the other of the first and second engagement members comprises projecting members that are locking received in the openings.
In another embodiment, the shell comprises a perimeter section surrounding a central section in which the flexible support section is provided and, when mounted on a chair, the flexible support section has a vertical extent sufficient to support at least the lumbar and mid back regions of the person when seated in the chair.
In another embodiment, the frame has an opening sized to receive therein the flexible support section.
In another embodiment, the flexible support section comprises a plurality of slats extending vertically between the perimeter of the flexible support section.
Another aspect of the invention provides a backrest for supporting a user""s back having a front surface and a rear surface, the backrest comprising: a shell having a perimeter section surrounding a central section and a plurality of slats extending vertically between the perimeter to occupy the central section and, when mounted on a chair, the slats have a vertical extent sufficient to support at least the lumbar and mid back regions of the person when seated in the chair; a frame having an opening sized to receive therein the slats; and, mounting members to mount the shell on the frame.
In another embodiment, the mounting members comprise first engagement members provided an the shell and second engagement members provided on the frame, the second engagement members are configured to engage the first engagement members whereby the engagement of the first and second engagement members retains the shell on the frame.
In another embodiment, the first engagement members and the second engagement members comprise a plurality of openings and the other of the first and second engagement members comprises projecting members that are locking received in the openings.
Another aspect of the invention provides a backrest for supporting a person""s back having a front surface and a rear surface, the backrest comprising: a flexible support section having a fixed end which is mounted to a support structure and a free end which is displaceable vertically with respect to the fixed end, the support section is configured to be compressed and displaced forwardly when the free end is moved towards the fixed end; an adjustment member drivingly connected to the free end; and, a detent member for selectively receiving the adjustment member in one of a plurality of positions, the support member biasing the adjustment member into retaining engagement with the detent member due to the compression of the flexible support member by the displacement of the free end towards the fixed end.
In another embodiment, the support structure comprises a frame and a shell mounted on the frame and the support section is provided as part of the shell
In another embodiment, the frame has an opening sized to receive therein the support section
In another embodiment, In another embodiment, the support member comprises a plurality of slats extending vertically between the fixed end and the free end of the support section.
In another embodiment, the slats extend from a position adjacent the fixed end to a position adjacent the free end.
In another embodiment, the shell comprises a perimeter section surrounding a central section in which the support structure is provided and, when mounted on a chair, the support structure has a vertical extent sufficient to support at least the lumbar region of the person when seated in the chair.
In another embodiment, the shell has first engagement members and the frame has second engagement members configured to engage the first engagement members whereby the engagement of the first and second engagement members retains the shell on the frame.
In another embodiment, one of the first engagement members and the second engagement members comprise a plurality of openings and the other of the first and second engagement members comprises projecting members that are locking received in the openings.
In another embodiment, the fixed end comprises the upper end and the free end comprises the lower end and the detent member comprise a plurality of vertically spaced apart members each of which has a downwardly extending recess and the adjustment member is sized to be received in each recess.
In another embodiment, the detent member comprises a plurality of vertically spaced apart members each of which has a recess to receive therein the adjustment member and support member biases the adjustment member into engagement with the recesses.
In another embodiment, the frame has a front face and a vertically extending opening adjacent the free end, the shell is mounted on the front face, the adjustment member is mounted at the free end of the support structure and has a handle which extends through the vertically extending opening whereby the support structure may be actuated from the rear of the backrest.
Another aspect of the invention provides a backrest for supporting a person""s back having a front surface and a rear surface, the backrest comprising: a flexible support section having a fixed end which is mounted to a support structure and a free end which is displaceable vertically with respect to the fixed end, the support section is configured to be compressed and displaced forwardly when the free end is moved towards the fixed end; an eccentrically mounted cam drivingly connected to the free end; and a locking member for retaining the free end at a fixed position with respect to the fixed end.
In another embodiment, the locking member comprises a detent and gear arrangement.
In another embodiment, the gear arrangement is mounted on a shaft.
In another embodiment, compression of the flexible support section biases the free end into engagement with the cam.
In another embodiment, compression of the flexible support section biases at least one tooth of the gear into locking engagement with the detent member.
In another embodiment, the flexible support section comprises a plurality of slats extending vertically between the fixed end and the free end of the support section.
In accordance with another aspect of the instant invention, there is provided a backrest a backrest for supporting a user""s back having a front surface and a rear surface, the backrest comprising a shell having a perimeter section surrounding a central section and a plurality of slats extending vertically between the perimeter to occupy the central section and, when mounted on a chair, the slats have a vertical extent sufficient to support at least the lumbar and mid back regions of the person when seated in the chair; a frame having an opening sized to receive therein the slats; and mounting members to mount the shell on the frame. This construction provides a simple and easily manufacturable flexible back rest for a chair.
The construction provides a lumbar adjustment mechanism which may be provided on a chair at a price point such that the chair may be purchased for non-executive positions such as secretaries, paralegals and the like. In addition, the mechanism is robust so that a chair encompassing this feature will provide reliable service.